Gaseous electric discharge apparatus



rPatentedimita1942- i ,t L a 2,270,368

- y umTEDy STATES; PATENT oFFlcE GAsEoUs ELECTRIC DISCHARGE APPARATUS Gustav Zecher, Eindhoven, ANetherlands;assignmto General Electric Company, a corporation of New, York Application December 29, 1938, Serial No. 248,288 l -In GermanyfFebi-uary 10, 1938 o i y Y 16` Claims. .(Cl. 1764.424) l This invention relates to a circuit arrangemain discharge tube and higher thanthe voltage ment'comprisinga gasnlled electric incandescent l supplied to its electrodesv after ignition of the electrode discharge tube,` an auxiliary branch.- main discharge tube when the thermally opercircui* connected in parallel withthis tube and ated switch is closed again.y i i comprisinga thermally operated switch which Since the heating elementof Vthe thermally is opened to ignite the tube, and an inductance v operated switch constitutes a series-element of connected in .series with the tube and the auxthe auxiliary branch circuit, noenergyiis supiliary branchcircuit! i ff i -plied any more to the heating elementafter the .y It has previously been proposed to short-cir-` 1 switch is opened; In theabsence cfa supply of cuit the discharge tube to be `ignited by means 10 energy theiswitching contacts very rapidly conof a switch. When this short-circuiting switch u tact again",lhowe`ver; also in this case no current is opened, a strong voltage impulse occurs in an w iiows throughtthe auxiliary branch circuit when inductance connected'n series with the disi n the main discharge tube has ignited, since the charge tube. In" order` to avoid the drawback auxiliary discharge tube provided in this circuit involved in the manual operation of this switch prevents the passage of current in the auxiliary it has already been suggestedtoemploy a therbranch -circuit due to the low working voltage mally operated switch, e. g; a bimetallic switch.- of Lthe main discharge tube during operation. With this thermally operated switch the open- The .heating element of Jtheswitch therefore .i ing of the switch is'eilected only after a certain consumes no energy during `operation fof the period, since the contact members are only sepa-` tube, While the arrangement exhibits an immerated from one another after a certain amount I diate readiness for ignition.` Since the auxiliary of `heat is supplied. The delay in ignition thus discharge tube exhibitsfan'arc discharge. a strong involved hasthe advantage, particularly with incurrent `iiows through the auxiliary branch cir` i candescent electrode? discharge tubes, that the cuit when the main dischargev tube is to be ignitincandescent electrodes may be heated prior to ed, which current upon opening of the switch the ignition of the tube which naturally favour-` leads to the production of a very strong voltage `ably affects its life and brings abouta lower f impulsein the pre-connected inductance. This igniting voltage than in the cold state of the permits also a more satisfactoryandmore rigid electrodes. f K l lconstruction *of the thermal interruptor, since After the tube has ignited,fthe contacts of the abundant energy may be supplied to the heating vthermally operated switch, by which the tube element prior to the ignition of the main disisbridged, must remain open `which requires the Y charge tube and thus the time of interruption supply of a certain amount of energy also durf may be reduced to about 1 to2 seconds, va time in ing normal operation ofthe discharge tube.This which generally also a sunicient lpre`.heating of l uselessly supplied energy entails another draw- 35 the incandescent electrodes is obtained. Since back. In fact, when the voltage supplied to the the energy required for opening the interruptor circuit arrangement is 'for some reason interdoes not play a part in normal operation ofthe .i frupted for a shortytimeand the discharge ex-` discharge tube andmay bo given a highl value. it "tinguishes, the thermally operated switch due to is possible to give the switch also a high contact its'ithermal delay needs a certain time until its 40 pressure so that a better interruption, better life switching contacts 'make contact again. `Conseof the' contacts `and a more favourable condition` v quently-in such cases the switch for initiating of ignition forthe tube is ensured. :the-ignition is not ready for use. v `It will be appreciated'that the auxiliary branch "The invention has for its purpose to avoid the l circuit need, not be connected directly jbetween t a abovementioned drawbacks. According `to the ,45 thefelectrodes of the main discharge tube, but invention'i the heating element of the thermally may be connected in parallel with this tube and t operated switch is inserted' in ytli'e auxiliary part of the pre-connectedimpedance. The points branch rcircuit in series with the switch.' Fur'- of connection of the auxiliary branchcircuit thermore an auxiliary discharge tube connected need only be such that the voltage supplied to in series with. the switch and the heating ele-50 the electrodes of the auxiliary discharge tube mentls inserted in this auxiliary branch circuit, i shall be suilicient for the ignition of the auxinwhich tube an arc discharge may occur. This iliary dischargev tube prior t0 the"ignitin` 0f the tube isso constructed and dimensioned that its main discharge tube, but shall be insuiilcient igniting `voltage is lower than the voltage suptherefor during'operation of the main discharge plied to its electrodes prior'to ignition oi' the u v y switch misma :any dname ou'slycomprlse a bimetallic switch'sothatitsz-metallicparts themselves 'actas' a heatingm element. An advanandv dimensioned tageous construction is obtainedwhen lthe yheat developed by theauxiliary discharge tubeis utilised to help the heating of the bimetallic elefastened' theftube `by means of a metallic strip thatthe `heatjiieveloped in the auxiliary discharge tubefistransmitted to the bimetallic strip by conduction 'or also by radiation and thus helpsthe heating of the latter.

. The-thermally operated switch and Vthe auxiliary discharge tube may advantageously be combinedl to form a unit so that an igniting de- ;.Tothisind'the bimetallic strip may be vice. is obtained which can be easily applied and connected.

The incandescent electrodes of the main discharge tube or, if desired, the heating bodies of these electrodes may advantageously be supplied with heating current from some turns of the inductance so that a special source of heating current is superfluous. The heating elements (with directly heated electrodes these are the core wires of the lelectrodes and with indirectly heat- 'hereinafter with reference to4 the accompanying drawing, in which the Figs. 1 and2 are two embodiments of the circuit arrangement according to the -inventionand Fig. 3 represents the constructional assembly of the auxiliary discharge tube with the bixnetallic switch.

In Fig. 1, I denotes a gasiilled discharge tube which, yfor example, may be slow-pressure mercury vapour discharge lamp provided, if desired,

with a luminescent coating on the glass wall.` The tube comprises two incandescent electrodes 2 and I and-is connected to thesource of alternating current ithrough the choke l. The electrode 2 is supplied with heating current by being connected across the end turns i of the choke coil l while the electrode 3 is supplied with heat- 'ing'cin'rent by being connected across the winding I which is `magnetically coupled with the chokecoil. l

vAn auxiliary branch circuit comprising the b1- -metallic switch I is connected in parallel with the discharge tube I The bimetallic strip of this switch is designated by l and the heating element of this bimetallic strip by Il. Furthermore the auxiliaryjbranch circuit comprises an auxiliary discharge tube II inwhich occurs an independent arc discharge. The switch l, the heating element I and the auxiliary dischargetube II are connected in series with one another and by reason of the operating characteristics of the tube Il constitute a non-linear circuit.

Since in the position of rest the switch I is closed and the auxiliary discharge tube II is so dimensioned as to be ignited when the supply voltage is applied and before a discharge starts in theztube; I, 'a current starts to now through the auxiliary branch circuit connected in parallel with theitube.v I-,Ieat produced in the element Il 'apropos then heats the bimetallic strip 9. After sunicient heating the bimetallic strip becomes curved with the result that the switch 8 is opened. Due to this interruption of the circuit a voltage impulse is produced in the choke 4 which brings about the ignition of the discharge tube. The ignition of this'tube is facilitated by the fact that the incandescent electrodes 2 and 3 during the passage of current through the auxiliary branch circuit are supplied with heating current from the turns i and 1 and consequently receive'a high temperature.

After the switch 8 is opened, no current nows through the heating element I0 so that the bimetallic strip 9 cools down and the switch I is closed again after some time. When the discharge tube I is ignited in the meantime, the voltage supplied to the auxiliary branch circuit has become lower than the voltage conducted to this branch circuit before the discharge tube I was ignited. In fact the voltage set up between the ends of the auxiliary branch circuit and consequently between the electrodes of the auxiliary discharge tube II has become equivalent to the working voltage of the discharge tube I. The auxiliary discharge tube II is so dimensioned that it will not continue to ignite with this voltage. Consequently after the main discharge tube I has been ignited no current flows through the auxiliary branch circuit connected in parallel with .the discharge tube I even when the switch l is closed again.l Thus it is ensured that this auiliary'branch circuit does not consume any current during normal operation of the discharge tube I and the current which flows upon ignition through this branch circuit may be given whatever highvvalue is desirable to obtain the operation of the bimetallic switch. -Also one obtains the advantage .that thev switch 8 is immediately ready to initiate the ignition again when the discharge in the tube becomes extinguished for any reason.

In the circuit arrangement according to Fig. 2 the preconnected choke coil of the discharge tube I comprises two parts `I2 and I3 which are connected at each end of the tube I. 'I'he incandescent electrode 2 is connected to some of the turns of the part I2 and the incandescent electrode 3 is connected to some ot the turns of the part I3 of the pre-connected impedance. The auxiliary branch circuit comprising the bimetallic switch 8 and the auxiliary discharge tube II is not directly connected between the electrodes of the discharge tube l, but between the end Il of the part l2 and the point I5 of the part I3. The

auxiliary branch circuit therefore is connected in parallel with the discharge tube I and the upper part of the choke coil I3. The point orconnec- 4tion I5 is so chosen that the voltage supplied to theauxiliary branch circuit after the discharge tube I has ignited is 'not sumcient to ignite the auxiliary discharge tube II. The connection ot the auxiliary branch circuit to point I5 has the advantage that not the wholepre-connected impedance of the discharge tube I is pre-connected with respect to the auxiliary branch circuit so that a stronger auxiliary current occurs than in the event of the auxiliary branch circuit being connected directly to the electrodes of the discharge tube.

As appears from Fig. 2, the auxiliary current iiows through the bimetallic strip 9 so that the latter constitutes at the same time the heating element for the bimetallic switch. In this case it is very desirable to help the heating of the Strip L;

iustrtecm rig. a, "",In' this'nsure. ,ileenetsihe millier-Y dis- I charge tube, The bimetalllclstripisalso in' this discharge tube Il.

Vworking voltage thereof,

bimetallic strip bymeans of the heat produced in `f"th`e dischargetube Il.y

chargegtube i ljis sderraiiged'that the heat produced tueren is transmitted@ the, bimetamc This `ensured in'the manner ile-f fForthispurposethediste the tube 1| byijnesns orstuememi strip vice .being less. than, that ,afraid gaseous device and greater than the working voltage thereof.

The contact" piece `I'l is connected tothe upper electrode of thedlscharge tube I|` by meahsbf the wire i9, wherea's'the lower electrode of tube and thestrip I6 areeachconnected to one of the contactpieces 2U. .These vcontactpieces are locatedv at` the lower end of thecap 2i of the glass envelope `22 which completely embraces the manner avery simple constructional unit is obtamed which may beleasly fnneite? in .parallel with the main diharge tube |31 i ,s

WhatI claim is:

` `1. In combination. a source of alternating cur-` rent supply, a gaseous electric discharge device connected to be supplied therefrom, `said device having electrodes arranged to be initially heated,

and a branch circuit including an auxiliary discharge device, a thermalswitch and means for heating the switch arranged in series `and connectedacross said gaseous device, the ignition voltage of said auxiliary device being less than that of said gaseousdevice and greater than the 2; In combination, a source lof alternating current supply, a gaseous electric discharge device connected to be supplied therefrom, said device having electrodes arranged to beinitially heated and a branch circuiti including an auxiliary discharge device, a bimetallic switch, and a resistance heater therefor arranged in series and connected across said Igaseous discharge device,the ignition voltage of said auxiliary device being less This envelope '22 `is preferably evacuated.` To supportythe discharge tube Il `against the` envelop'e 2 2, amica discj23fis provided at the upper end of the `tube Il. In thisv charge device `coniiected ignition voltage of said au L than that of said gaseous 5; In combination,-afsurcepflalternating cur-v rent supply, aballast reactor, "`a ga seo us electric Xdiahafrser through said reactor, said device having spaced electrodes thereim frornjsaid reactor tosaid device connectedwith said source means for Supplying energy i i i i electrodes i initially heat them, and a branch circuit connected across 4said device and including a heater, a thermalv switch adjacent theretoand an `auxiliary distogether {in series, the Xilialfy device 1888 discharge device connected., ,with` said` source through said reactor, said, devicefhaving spaced electrodes therein, means 1 ignition 4voltage of said' auxiliary devicebeing less than that of said` gaseous device` aridgreater than the workingvoltage thereonl 1` v j '1. In combination, a source ofalternating cur- 8 0,

rentfsupply, a ballast reactor,a. gaseousv` electric discharge device connected with ,said source Vthroughsaid reactor, said vdevice having `electrodes arranged to be initially heated and a branch circuit including a `thermal switch, a

heater therefor and an auxiliary discharge device connected together in'series, said branch circuit than that oi said gaseous device and greater than the working voltage thereof.

3. In combination, a source of alternating currentsupplv. a gaseous electric discharge device connected to be `supplied therefrom, said device having electrodes arranged to be initially heated anda branch circuit arranged to shunt said device including an auxiliary discharge device and "a thermal switch connected together in series, said auxiliary device being arranged in heat con-l 1 ducting relation withsaid switch, the ignition voltage of said auxiliary device-being less than y that of said gaseousdevice andgreater than the working voltage thereof.

4. Incombination`, a source of alternating current supply, a gaseous electric discharge device connected to be supplied '-therefrom, said device having electrodes' arranged to be initially heated and a-branch circuit connected across said device including'a thermal switch and an auxiliary discharge device a switch, the ignition-.voltage of said'auxiliary devedto supply heatto said being connected in shunt with said device and an adjacent portion of said reactor, the ignition voltage of said auxiliarydevice being less than that of said gaseous device and greater than the working voltage thereof.

8. In combination, a source of alternating current supply, a ballast reactor, a gaseous. electric discharge device connected with said source through said reactor, said device having spaced electrodes therein, means for supplying energy to said electrodes to initially heat them including a tap on the reactor connected with one electrode and a winding associated with the reactor and connected across the other electrode, and a branch circuit connected across the` device in` cluding a thermal switch, a heater therefor and an auxiliary discharge device connected together in series, the ignition voltage' of said auxiliary device being less than thatof `said gaseous device and greater than the working voltage thereof.

9. In combination, a source of alternating curf rent supply, a gaseous electric discharge device connected to be supplied therefrom, said device including electrodes arranged to be supplied, with heating currentl and means for controlling said heatingcurrent comprising a circuit arranged to v shunt said device, said circuit not including said electrodes `and including a thermal switch and means for supplying heat thereto.

10. In combination, 'a gaseous electric Vdischarge lamp having spaced electrodes, means including a ballasting impedance for operatively connecting said lamp with a source of alternata ing current supply, at least one of said electrodes 'being nlamentary and arranged to be supplied withcurrent'i'or the preheating thereof, and a circuit connected in shunt with said lamp and not including said electrodes for controlling said preheating current, said circuit including a bievice andgreater than Athe working voltage thereof, f ll?. "In combinati n`, a source i of alternating cur- "`rent supply, a ballast' reactor,a gaseous electric i for supplying heating currentto one of said electrodes from aportion of said reactor and a branch circuit connected across said device v,and including `a heater, a f thermal switchadjacent thereto andan auxiliary discharge devicefccnnected together in vseries, the

metallic switch and a heating resistor therefor.

' 11. Inl combination, a gaseous electric discharge lamp having iilamentary' electrodes, means includlng a ballastreactor for connecting it to be supplied from'a source of alternating current, and means for controlling theA ilow of current through` said"electrodes for producing an initial heating thereof comprising a thermal switch and a resistance vheating member therefor connected in a circuit shunting said lamp but not including the lamp electrodes.

vice comprising a closed tube having spaced electrodes therein arranged to be supplied with heating current, Ymeans for connecting said device to be supplied from a source of current, and means for controlling said heating current comprising a circuit connected between said electrodes and shunting the arc path, said circuit including a thermal switchand heating means separate from I12.y In combinatioman electric discharge devicehaving spaced electrodes therein, one ofl said electrodes being arranged to be supplied with heating current, means for connecting said `device to be supplied from alsource of current, .and means for controlling'said heating current comprising a circuit connected between said electrodes, said circuit including a thermal switch and a `resistor independent of said one electrode for supplying heat thereto.

` 13. In combination, an-electric discharge device Vhaving spaced electrodes therein constructfrom a source of current, and controlling means ed to be heated by current flow therethrough, means for connecting said device to be supplied for said electrode heating currentvcomprising a circuit shunting the discharge path through said device and including a thermal switch and resistance heating means therefory located outside of saidfdevice. j v l 14. In combination, an electric discharge deand independent of said electrodes and located externally of said tube` for supplying heat to said switch;l

15. In combination, an electric discharge devicehaving spaced electrodes therein, at least one'of which is of the fllamentary type` arranged to be supplied with heating current, 'means for connecting said device to a source of current and means for controlling said heating current comprlsing a circuit connected between said electrodes, said circuit including a bimetallic switch and a resistor for supplying heat thereto.

16. In combination, an electric discharge device having spaced electrodes, at least one of which is of the Vfilamentary type arranged to be supplied with lheating current, means for connecting'said device to a 'source of current and a circuit connected between the elecitrodes and shunting thearc path for controlling said heating current, said circuit including a bimetallic member anda resistor in series therewith for supplying heat to said bimetallic member.

GUS'IAV ZECHER. 

